Abstract: Based on the investigation and analysis of the macroscopic ground rupture zone caused by Changma earthquake(M_s =7.5)which occurred in the western Qilian Mountains, Gansu province on December 25, 1932. and combining the information relative to fault activity with the results of lab modelling experiments, this paper pays much attention to the discussion of the tectonic evolution of Changma causative fault and the rupture slip process at the places of stress concentration within seismogenic fault.The rupture zone on ground caused by the event, with a NWW of trend and a length of more than 120 km, consists of three reversed-S-shaped seismic demation belts, and coincides with the Quaternary active trace of Changma faults. Both field geological information and modelling experiments have indicated that the concaves of the turning sectors of the reversed-S-shaped faults are the places at which the stress and strain would be concentrated easily. Here, a model of the multi-initiative points of the rupture slip within Changma seismogenic fault has been suggested, i. e., when the Changma event occurred, each of the concaves of the above kinds ruptured initiatively, then was developing along the above-mentioned reversed-S-shaped fault's trace so as to form the whole Changma seismic fault.

Key words: Changma, Peversed-S-shaped, Rupture slip process

摘要： 以1932年12月25日发生在甘肃省境内祁连山西部的昌马地震(M_s=7.5)造成的宏观地表破裂带的调查与分析为基础,结合有关断裂活动的资料与室内模拟实验结果,本文着重探讨昌马地震发震断裂的构造演化及其应力集中部位的破裂错动过程。从宏观的角度提出了多破裂错动起始点的昌马地震断层模式。

关键词: 昌马, 反S型, 破裂错动过程